Stainless steel processing characteristics and selection of milling cutters
What milling cutter is used for machining stainless steel? This is a problem that many people often encounter. If customers encounter problems such as chipping and work hardening when machining stainless steel.
Compared with the workability of 45# steel, the workability of austenitic stainless steel is only 0.4, ferritic stainless steel is only 0.48, and martensitic stainless steel is only 0.55. Among them, the machinability of austenite and carbonate mixtures is poor.
1. Severe work hardening
The work hardening of stainless steel is severe. The first choice is a mixture of austenite and ferrite. The hardness of the hardened layer is 1.4~2.2 times higher than that of the original matrix, and the strength is R=1470~1960MPa. This type of stainless steel has a large plasticity and a large strengthening coefficient. Moreover, austenite is unstable and easily transformed into martensite under the action of cutting force.
2. Large cutting force
Stainless steel has high plasticity, especially the depth rate of austenitic stainless steel is 2.5 times that of 45# steel. During the milling process, the plastic deformation is large, the cutting force is increased, the work hardening is serious, the thermal strength is high, and the cutting curling and breaking are difficult.
3. High cutting temperature
The plastic deformation of stainless steel is large, the friction is increased, and the thermal conductivity is low. Therefore, under the same conditions, the temperature of milling stainless steel is about 200 degrees higher than that of No. 45 steel.
4, Cutting is not easy to break
When machining stainless steel, it is easy to bond and produce built-up edge. The plasticity and toughness of stainless steel are relatively large, and it is not easy to break during milling. Under high temperature and high pressure, the tool is prone to adhesive wear and built-up edge.
5. The tool is easy to wear
Of course, stainless steel milling cutters must be used for machining stainless steel, because the TiC hard spots of stainless steel can easily cause severe grinding and wear of the tool. Under high speed, high temperature and high pressure conditions, cutting tools are prone to sticking, diffusion and crater wear.
What milling cutter is used for machining stainless steel?
When doing stainless steel processing, it is best to choose materials with high hardness, good wear resistance, good strength and toughness, and good thermal conductivity.
Carbide material: YG, YW, etc. Use tungsten-cobalt fine-grained or ultra-fine-grained cemented carbide containing TaC or NbC. Such as YG6x, YG813, YW4, YD15, etc.
High-speed steel material: W6Mo5Cr4V2Al, W10Mo4CrV3Al, etc.
For milling 201, 304 and other ordinary stainless steel materials, choose ordinary carbide-coated milling cutters, and choose 4 blades for milling. Secondly, major CNC tool suppliers have special stainless steel milling cutters. If the customer is not price sensitive, this type of knives can be chosen. If processing 316 stainless steel, stainless steel after quenching and heat treatment, imported and high-hardness stainless steel, in addition to using high-hardness knives, the cutting edge of stainless steel must be sharper, and it is best to use special stainless steel knives of various well-known brands.
Stainless steel machining can be divided into rough machining and finishing. Rough machining can choose YW and YT cemented carbide with relatively low TiC content. For finishing, you can choose YW and YT carbide with high TiC content. .
Secondly, when machining stainless steel, in order to prevent the edge from chipping, the strength of the blade should be increased, and the rake angle is best to choose a smaller value or a negative value. If machining stainless steel with carbide, the helix angle is preferably 5-10 degrees. If using a high speed steel end mill, 35-45 degrees should be selected. When milling stainless steel, it is best to choose an end mill with a larger helix angle, and when milling stainless steel pipes or thin-walled workpieces, you can choose a corn end mill.
Commonly used stainless steel milling amount
For carbide stainless steel milling cutters, the milling speed should be 40-60m/min. In order to avoid cutting edges in the hardened layer and accelerate tool wear, the feed rate should be greater than 0.1mm.
High-speed steel end mill, cutting speed 8-40m/min, feed rate 0.013~0.15mm/z.
Other knowledge of processing stainless steel
1. When processing high-hardness stainless steel, it is best not to use high-speed steel end mills.
2. If the hardness of the steel is higher, select a lower milling amount.
3. When the amount of side cutter is large, choose a lower milling speed.
4. Using coated carbide tools, the milling speed can be increased by about 50%.
5. Pay attention to sufficient cooling when cutting. If using cemented carbide tools to process stainless steel, do not use water-soluble cutting fluids, so as to avoid chipping caused by large thermal stress on the cutting edge.
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